Oh, i don’t think anything can cause a lasting wedge between the characters at this point.
Regina has tried to murder everyone in Snow’s family on multiple occasions, did murder Snow’s father, her mother murdered Snow’s mother, Snow murdered her mother, and Henry almost died from eating the poisoned turnover. Regina is still part of the family.
Hook has tried to shoot Belle, stab her with a Hook, has stabbed Rumpel with a Hook. He and Belle are friends now.
Hook has tried to kill Emma, tried to separate her and Snow from their families forever, and tried to murder the entire family just last season. They are dating.
Zelena kidnapped Rumpel, murdered Bae, raped Robin. She is part of the family.
If Hook killed Charming’s dad, it might cause a tiff, but nothing long lasting. Not based on how much people hang out and date their would be murderers on this show. It is just a theory though. It could be some happy connection instead.